Which ocean is the largest and deepest of Earth's oceanic divisions?

The Pacific Ocean is the largest and deepest of Earth’s oceanic divisions.

It covers about 165.25 million square kilometres—roughly one-third of Earth’s surface—and contains around half of the World Ocean’s water by volume. Its average depth is approximately 4,000 metres, although the deepest known point on Earth, Challenger Deep, lies within the Pacific’s Mariana Trench.

The name comes from Portuguese and Spanish exploration: Vasco Núñez de Balboa called it the “South Sea” after reaching it in 1513, while Ferdinand Magellan later described its waters as peaceful and popularized the name Pacific. The ocean stretches between Asia and Australia on one side and North and South America on the other.

A common mix-up is confusing the Pacific’s size with the Atlantic’s historical importance or confusing the Pacific Ocean with the larger geographic “Pacific basin.” The Pacific is also gradually shrinking along several boundaries as tectonic plates subduct beneath surrounding plates.